Structures

ABSTRACT

A multi-cell structure, for example an aircraft wing, comprising polygonal support members or spines and panel members bonded to the spines so that a median plane of a panel member intersects one side of a spine and the panel member is bonded to two other sides of the spine.

United States Patent 1191 Jones Nov. 13, 1973 STRUCTURES [75 Inventor:Michael Weston Jones, Droitwich, WV yorcestershire, England v [73]Assignee: Imperial Metal Industries (Kynoch) Ltd., Birmingham, England[22] Filed: Oct. 10, 1972 211 Appl. No.2 296,230

Related u.s. Appllcatlon Data [63] Continuation of Ser.' No. 1,073, Janv5, 1970,

abandoned.

[52] US. Cl 244/123, 52/615, 161/68,

[511 rm; cl. B64c 3/20 58 Field of Search 244/119, 123, 131; 52/615,650; 161/68, 69; 156/299 [56] References Cited UNITED STATES PATENTS2,540,482 2/1951 Hervey 244/123 3,667,984 6/1972 Adams 161/68 UX2,316,622 4/1943 3,416,750 12/1968 Young 161/68 X PrimaryExaminer-Milton Buchler Assistant Examiner-Galen L. BarefooAttorney-Akin T. Davis 1 57 I ABSTRACT A multi-cell structure, forexample an aircraft wing, comprising polygonal support members or spinesand panel members bonded to the spines so that a median plane of a panelmember intersects one side of a spine and the panel member is bonded totwo other sides of the spine. I

4 Claims,'3 Drawing Figures PATENIEDMUY 13 ms 3771. 748

SHEET 16F 2 FIG.2.

STRUCTURES This is a continuation of application Ser. No. 1,073 filedJan. 5, 1970, now abandoned.

BACKGROUND OF THE INVENTION This invention relates to structures whichmust withstand stress imposed therein by bending, shearing, torque ortensile loads or combinations thereof.

A typical example of a structure which has to withstand such stresses isan aircraft wing which, especially during landing and take-off of theaircraft, is subjected to complex stresses. For instance,twistingmoments are applied to'the wing by the reaction of the ailerons againstatmospheric air; bending moments arise from the cantilever arrangementof the wing with respect to the aircraft fuselage; and direct loads maybe applied by undercarriage assemblies and'fuel tanks, etc. located inthe wing. Also during flight stresses are 'imposed by the rolling,pitching and yawing of the aircraft.

Usually lightweight structures are'made by welding together tubular orother suitably sectioned framemembers, or by bolting together the framemembers with the aid of angle brackets.

lf fibre-reinforced plastics materials could be employed, bondedsurfaces would have a high resistance to shear stress, i.e. tangentialto said surfaces, but would be'relatively weak in tension whencomponents of force are exerted in a direction normal to the bondedsurfaces and consequently the bonded surfaces would tend to peel apart,particularly if low modulus material is used. If bolts or rivets, etc.are utilised in the structure, the necessary holes and the presence ofstressed cut edges seriously reduce the static and fatigue strength ofthe structure.

, SUMMARY OF THE INVENTION According to the'present invention astructure for withstanding stressesv imposed therein by bending,

'a'median plane of each panel member intersecting oneofsaid planar sideswhich is intermediate two other planar sides, each panel member beingbonded to said two other planar sides so that the median plane of eachpanel member forms an angle greater than 90 with one of said otherplanar sides, and forms an angle of between 90 and 180 inclusivewith'the remaining said other planar side.

Preferably the median plane of each panel member forms an angle greaterthan 90 with both of said other planar sides. v

In a preferred arrangement, the median plane of each panel member isnormal to said intermediate planar side.

The panel members may themselves have extensions integrally formedtherewith for bonding to said two other planar sides, or additional tiemembers may be provided to connect the panel members with said twoother. planar sides.

If required, the structure may comprise a plurality of support memberseach having an outer surface which is polygonal so as to have aplurality of planar sides, and

aplurality of panel members, the. median plane of each 2 panel memberintersecting one planar side which is intermediate two other planarsides of a support member, the respective panel member being bonded tosaid other planar sides, and at least one panel member being connectedto each two adjacent support members to connect them together.

Each panel member may comprise two parallel walls and extensions of thewalls which diverge from one another in the vicinity of a supportmember, each extension being bonded to one of said two other planarsides of the support member.

In accordance with the invention also, a structure for withstandingstresses imposed therein by bending, shearing, torque or tensile loadsor combinations thereof comprises at least one support member of whichthe outer surface is polygonal and a plurality of shell members, eachshell member having with respect to the longitudinal axis of the supportmember, a radially inner flat wall and a radially outer wall, and twoopposed flat walls connecting the longitudinally extending edges of theradially inner and outer walls, the radially inner flat wall of eachshell member, being bonded to one of two planar sides which extend atopposite edges of an intermediate planar side of the support member, theopposed flat walls of adjoining shell members being bonded together toform corresponding panel members, each of which extends from arespective intermediate planar side.

Preferably each panel member formed by adjoining shell members is normalto its respective said intermediate planar side of an associated supportmember.

7 The walls of each panel member may be spaced from one another by anintermediate layer of metal honeycomb or rigid plastics foam.The metalhoneycomb may be secured to the support member by a layer of foamedadhesive.

The support member may be hollow with its interior 1 either vacant orprovided with 'a core of foamed plastics, elastomeric material, or othersuitable-filler material to provide additional stiffness or to provide adamping medium.

The support member and shell members may be made, for example, fromglass reinforced plastics material or carbon fibre reinforced plastics;material.

The invention also consists in a method of manufacturing a structure forwithstanding stresses imposed therein by bending, shearing, torque ortensile load or combinations thereof, comprising, forming a supportmember of which the outer surface is polygonal so as to have a pluralityof planar sides, forming a plurality of shell members, each shell membercomprising with respect to the longitudinal axis of the support member,a radially inner flat wall and a radially outer wall, and two opposedflat walls connecting the longitudinally extending edges of the radiallyinner and outer walls, disposing said shell members around the supportmember so that the radially inner flat surfaces locate against planarsides of the support member and adjacent flat walls of adjoining shellmembers are parallel so as to form panel members, each of which extendsfrom intermediate planar sides of the support member, securing theradially inner flat surfaces of the shell members to the support member,and securing the adjacent flat walls of adjoining shell members to oneanother.

BRIEF DESCRIPTION OF THE DRAWINGS In order that the present inventionmay be more clearly understood three embodiments of the invention willnow be described, with reference to the accompanying drawings in which:

FIGS. 1 and 2 are lateral sectional views of part of an aircraft wingaccording to a first and second embodiment, respectively, and

FIG. 3 is a diagrammatic plan view of a satellite structure according toa third embodiment of the invention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring to FIG. 1 of thedrawings, a structure for an aircraft wing comprises a plurality ofhollow support members 10 of which four are shown in the drawingarranged in vertically aligned pairs spaced apart across the wing, eachsupport member extending in a direction along the length of the wing.Each support member 10 in lateral cross-section is polygonal so as topresent an outer surface having a plurality of planar sides 110,1 1b. Inthis first embodiment, each support member 10 has six planar sides ofwhich five, denoted by numeral 11a, are of equal width and the sixth,denoted by numeral 11b is of greater width and faces externally of thestructure. The hollow interior of each support member 10 is left vacant.

Between each group of four support members, there is arranged a seriesof shell members 12, each of generally rectangular shape and comprisingflat walls 13, adjacent walls of each shell member being connectedtogether by narrow walls 14 forming an angle of 45 with the associatedwalls 13. The width of each narrow wall I -lss samt y fil s amq as tfths n aaar id lla of the siippbrt members.

. nated with an epoxy novalac resin, hardener and acetone mixture,comprising:

40 parts by weight of resin LY558 1.5 parts by weight of hardener 60parts by weight of acetone available from CIBA (A.R.L.) Ltd.

The solvent is then driven off by heating at 100C in a suitable oven.

The appropriate number of sheets of unidirectional carbon fibre are laidup onto respective complementarily shaped metal mandrels, in therequired fibre pattern, and the assemblies are cocooned in a layer ofpolytetrafluorethylene, a bleed cloth to absorb surplus resin solutionand a rubber bag. The assembly is then submitted to an autoclave cycleof 2 hours at 165C and 70-80 p.s.i. Whilst the support members and shellmembers are still on their mandrels they are post-cured for 2 hours at180C. The mandrels are then extracted from the members.

To fabricate-the structure the required number of support members andshell members 12 are assembled in a suitable jig, a narrow wall 14 beinglocated in contact with a corresponding planar side 11a of a supportmember, and opposed flat. walls 13 of adjoining shells 12 disposedparallel to but spaced from one another to provide therebetween a cavity15 into which a layer of aluminium honeycomb 16 is inserted. The upperand lower outer surfaces of the structure are provided by layers 17 ofcarbon fibre skin which are spaced from the upper and lower walls 13 ofthe shell members to provide further cavities 15 for the insertion ofaluminium honeycomb 16, the layers 17 extending over and being disposedagainst the planar sides 11b of support members 10.

Each layer of honeycomb 16 is secured between two channels 18 by meansof foamed adhesive 19 which also serves to stiffen the edge of the layerof honeycomb 16.

The shell members are bonded to the support members by a film adhesive,typically of a type denoted BSL308 and available from CIBA (A.R.L.) Ltd.The adhesive is applied to the surfaces to be bonded prior to assembly.The adhesive bond is cured at 165/175C for one hour. The bonding jig isdesigned to exert adequate pressure over the total bond area.

Thus opposed vertical flat walls 13 of adjoining shell members 12together with the intervening honeycomb l6 constitute vertical panelmembers 20. Similarly, the horizontal flat walls 13 and layers 17together with the intervening honeycomb l6 constitute horizontal panelmembers 21. Furthermore, the narrow walls 14 and the portions of thelayers 17 which are bonded to support members may be considered asextensions of the walls 13 and which diverge from one another at thesupport members. Thus each panel member interconnects two adjacentsupport members. In the structure of FIG. 1, each shell member 12, inrelation to the longitudinal axis of one associated support member 10,comprises a radially inner flat wall 14 bonded to the member, and adiagonally opposite and radially outer flat wall 14 bonded to anothersupport member.

It will be clear from FIG. 1 that a median plane of each panel member20,21 intersects one planar side 11a which is intermediate two otherplanar sides of a support member 10 and that each panel member is bondedto said two other planar sides.

It will also be evident from FIG. 1 that the median plane of each panelmember forms an angle greater than with each of the two respectiveplanar sides to which the panel member is secured.

In the manufacture of an aircraft wing, the usual skin 22 is appliedover the above structure.

In use of an aircraft wing based on the above structural arrangement,tensile forces induced in the walls 13 during the various phases ofaircraft movement are transmitted to the support members 10. Such forcesare distributed across the bonded surfaces of the narrow walls 14 of theshell members 12, and the respective planar sides 11a of the supportmembers 10 to cause a reaction in shear stress across the whole area ofthe respective planar sides 11a, rather than tensile stresses liable toproduce peeling. The absence of bolts or rivets in the structure avoidsstructural discontinuities by eliminating cut edges formed by holes orslots along the narrow walls 14 and planar sides 11a, and avoidsconcentrated loading points, the adhesive bond promoting a uniformdistribution of stress.

In a modification the hollow support members 10 may have their interiorsfilled, for instance, with a core of elastomeric material to assist indamping out vibration.

In a second embodiment, shown in FIG. 2, a structure for an aircraftwing is similar to that of the first embodiment in that it compriseshollow support members 10 and shell members 12 as described in the firstembodiment. However, in this second embodiment upper and lower layers ofshell members are provided and intermediate the two layers there aredisposed a plurality of hollow regular octagonal support members 23 eachpresenting an outer surface having planar sides 24.

It will be apparent from an inspection of FIG. 2 of the drawing that thestructure is also assembled in a similar manner to that described in thefirst embodiment except that additional intermediate panel members 25are provided by sandwiching a layer of aluminium honeycomb 26 betweenflat walls 13 of adjacent upper and lower shell members 12. l

A third embodiment illustrated in FIG. 3 relates to a satellitestructure which, in flight, is subject to centrifugal forces andconsequent tensile loads imposed by spinning of the structure. In thissatellite structure two hollow octagonal support members 30, 30a eachhave eight planar sides 31. Each of two substantially rectangular shellmembers 32 comprises, for instance, with respect to the support member30, a radially inner flat wall 33, and a radially outer wall 34, thelatter being constituted by three distinct parts denoted respectively35, 36 and 37. The longitudinally extending edges of the radially innerand outer walls are connected together by two flat walls 38. Four shellmembers 39, each in the shape of a quadrant and comprising a radiallyinner flat wall 40, a radially outer curved wall 41 and flat walls 42,are disposed two at each side of the pair of shell members 32, theradially inner flat wall 40 of each shell member 39 being bonded to arespective planar side 31 which is intermediate two other planar sidesof a support member 30, 30a. Honeycomb structure 43 is sandwichedbetween and bonded to opposed walls of adjoining shell members toprovide panel members 44, and paddle hinge brackets 45 are inserted inappropriate panel members as required for hingedly mounting solarpaddles (not shown) to the structure.

From FIG. 3 it will be seen that each octagonal support member 30, 30ahas four shell members bonded to alternate planar sides and that fourpanel members 44 extend normal to the remaining intermediate planarsides of each support member, the central panel memher interconnectingthe two support members 30, 30a.

in any of the above embodiments, the metal honeycomb may be replaced byplastics honeycomb made with Nome (Registered Trade Mark) paper.

Alternatively, the walls of the panel members may be spaced from, andbonded to one another by rigid plastics foam.

I claim:

l. A stress bearing structure for flight vehicles, the structurecomprising at least one elongated beam-like support member of polygonallateral cross-section such that the outer surface has a plurality ofplanar sides each of which is intermediate other planar sides, aplurality of shell members, each shell member being of unitaryconstruction and having, with respect to the longitudinal axis of saidat least one support member, a radially inner flat wall and a radiallyouter wall, and a flat wall connecting each longitudinally extendingedge of the radially inner wall with a respective longitudinallyextending edge of a radially outer wall to form a closed quadrilateralfigure, the radially inner flat wall of each shell member being bondedto a respective one of said other planar sides of the support member,the arrangement being such that the opposed connecting flat walls ofadjoining shell members are parallel one to the other and are bondedtogether to form corresponding panel members each of which extends froma respective one of said intermediate planar sides of the supportmember.

2. A structure according to claim 1 wherein each panel member formed byadjoining shell members is normal to its respective said intermediateplanar side of an associated support member.

3. A structure according to claim 1 wherein the support members and theshell members are made from glass reinforced plastics material.

4. A structure according to claim 1 wherein the support members and theshell members are made from carbon fibre reinforced plastics material.

'UNHED STATES PATENT OFFICE @ERTEFICATE ()F CORRECTION Patent No.3,771,748 Dated November 13 1973 Inventor) Michael Weston Jones It iscertified that error appears in the above-identified patent and thatsaid Letters Patent are hereby corrected as shown below:

In the heading, line 30 was omitted and should appear as follows:

[30] Foreign Application Priority Data Jan. 20, 1969 Great Britifln 335/ 9 Signed and sealed this 9th day of April 19m. I

(SEAL) Attest:

0'. MARSHALL DANN- EDWARD M.FLETCHER,JH.

Commissioner of Patents Attesting Officer ORM PO-IOSO (10-69 USCOMM-DCscan-pea

1. A stress bearing structure for flight vehicles, the structurecomprising at least one elongated beam-like support member of polygonallateral cross-section such that the outer surface has a plurality ofplanar sides each of which is intermediate other planar sides, aplurality of shell members, each shell member being of unitaryconstruction and having, with respect to the longitudinal axis of saidat least one support member, a radially inner flat wall and a radiallyouter wall, and a flat wall connecting each longitudinally extendingedge of the radially inner wall with a respective longitudinallyextending edge of a radially outer wall to form a closed quadrilateralfigure, the radially inner flat wall of each shell member being bondedto a respective one of said other planar sides of the support member,the arrangement being such that the opposed connecting flat walls ofadjoining shell members are parallel one to the other and are bondedtogether to form corresponding panel members each of which extends froma respective one of said intermediate planar sides of the supportmember.
 2. A structure according to claim 1 wherein each panel memberformed by adjoining shell members is normal to its respective saidintermediate planar side of an associated support member.
 3. A structureaccording to claim 1 wherein the support members and the shell membersare made from glass reinforced plastics material.
 4. A structureaccording to claim 1 wherein the support members and the shell membersare made from carbon fibre reinforced plastics material.